Do I have a virus?

My computer keeps just shutting down abruptly. It switches itself off and back on again. Windows media centre 2005. Zone Alarm protection.

Any ideas? Ive ran spybot and Lavasoft Ad-aware.

Do I have a virus?antivirus downloads

There a number of possibilities here. the most likely is that an individual component in the computer has failed. If the computer shuts down while you are using it check the CPU fan, because as a safety feature most computers are set to shut down if the CPU overheats. If the computer shuts down as soon as you turn it on, you should take it to your nearest computer shop for them to look at. The other possibilities include 1) windows fatal error: for this do a windows reinstall. 2) program fatal errors: will need to be debugged by a technician or 3) a virus that zone alarm did not pick up. Once again you will need to take the computer to be serviced

Do I have a virus?cafe racer

Check out the links below %26 you will have your answer.
Aside from the previous answers, often the reason a pc will shut down and reboot is due to excessive heat inside the case, particularly with the CPU chip. Open the case, and carefully check to see if all your fans are running properly. Good luck.
It could be a virus, a motherboard failure, or a hard drive failure.

If you hear a strange noise from your PC and it speeds up and slows down, it could be a hard drive failure. If there are no effects

and it just seems to shutt on and off with no warning, it could be a virus. If you occasionaly loose grafics, or your computer's disk drives occasionally go inoperative you could have an iminant motherboard failure. Nevertheless, you should back-up your files and try to see if it is a virus VIA virus software. If you don't find a virus, take your computer down to the shop, and let them check it out, and see where the failure resides.......